Watermarking Your Images

Introduction to watermarking

The watermark capability in Pixaria works by compositing a transparent PNG image on top of the photo being watermarked at the time it is displayed to the user. The PNG image 'watermark.png' is located in the images folder of the current theme being used by Pixaria. Themes can be managed in the appearance control panel in Pixaria's administration website.

Image watermarking is performed dynamically every time the image is sent to a user's web browser. Enabling watermarking can therefore increase the CPU load on your website which may cause performance issues on budget, shared hosting servers.

Changing the watermark image

If you wish to change the watermark image, you will need to use an image editing program to create a 24 bit transparent PNG file (one with an alpha channel). Photoshop, Fireworks and ImageReady all have the capability to create PNG images of this kind.

You can easily create a new watermark file in Photoshop. Begin by creating a new image with dimensions no bigger than about 300 x 300 pixels in RGB colour with a transparent background. Next create a new layer on top of the background and draw your design onto it. You may wish to reduce the opacity of the layer with the design in so as not to completely mask the images you want to watermark.

When you're happy with your design of watermark image, you will need to save it as a PNG file. To do this, go to the File menu and then 'Save for web'. In the window that opens up, select PNG 24 from the presets panel on the right of the screen and ensure that 'transparent' is checked. Save the file and you have your new watermark.

The watermark image should be located in the folder of whichever theme you are currently using with Pixaria. The watermark image is stored in the images directory of your chosen theme:

themename/images/ui/watermark.png
To use your own watermark image, replace the default image in your custom theme with one you have made yourself.

Changing the watermark position

You can change the location of the watermark on your images. Available options include centre, top left, top right, bottom right and bottom left. These options can be found in the appearance control panel.

Troubleshooting

When watermarking is turned on, web preview images do not display at all.

  1. You must use a 24 bit PNG image with an alpha channel as the watermark image file.
  2. You must have an up to date installation of the GD graphics library (see the status pages in the admin control panels).

Images are visible but without the watermark.

  1. You may be viewing a cached copy of the image. Refresh your browser.
  2. Check the settings for watermarking in the admin control panel. It's possible to configure watermarks to only appear for unregistered users.

I've changed my watermark but my images still show the old watermark.

Watermarks are applied dynamically so if you change the watermark, it will affect all images. Thumbnails, and web preview images are all cached aggressively so you may need to refresh your browser or clear the cache to see any changes.

Watermarks are not appearing on thumbnail images.

Watermarking of thumbnail images isn't currently supported because of the performance strain this would place on the web server. For a page with hundreds of thumbnails, the server resources required to dynamically generate this many thumbnails would cause performance problems for the entire site.



Last edited on Thursday May 31 2012 at 01:21:25

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